Field of Disclosure
The present disclosure concerns a gas turbine engine, a compressor, and/or a method of manufacturing a gas turbine engine and/or a compressor.
Description of Related Art
Gas turbine engines are typically employed to power aircraft. Typically a gas turbine engine will comprise an axial fan driven by an engine core. The engine core is generally made up of one or more turbines which drive respective compressors via coaxial shafts. The fan is usually driven off an additional lower pressure turbine in the engine core.
A compressor typically comprises a series of arrays of blades each having an aerofoil cross section. The blades are attached to a central hub or drum. The blades accelerate the air through the engine. Each of the arrays of blades are coupled with an array of vanes that are also of aerofoil cross section. The vanes are connected to radially inner and/or outer casings.
The vanes may be variable guide vanes. That is, the vanes may be moveably attached to the inner and/or outer casing such that each vane can rotate relative to the casing about an axis local to the vane. Rotating the vanes can vary the angle of approach of air to the vane as seen from the vane, and/or vary the exit angle of air from between the vanes, so as to optimise performance of the engine at a given operating condition.
Generally, each of the vanes are pivotally connected via a lever arrangement to a unison ring. The unison ring moves circumferentially (either anti-clockwise or clockwise as desired) so as to change the angle of the vanes. A lever pin (forming part of the lever arrangement) is mounted to the unison ring. A bush is provided between the lever pin and the unison ring. Retention features are provided to axially retain the pin with respect to the unison ring. However, in current designs, the retention features can often be damaged during assembly, which can reduce their effectiveness.